Recently i came across another interesting issue where,
When browsing report server URL and then viewing any report that spans multiple pages shows 0 of 0 pages in the tool bar. This also disables the page navigations.
You'll see a very similar behavior when viewing the reports from Report manager as well. The difference here is, the page navigations are enabled and it works eventhough it shows 0 of 0 pages and it doesn't change when we move to next page.
You'll not see any error message either in the page or in the log files.
The same reports work fine from BIDS.
Resolution for this issue is the same as the one which i posted here,
Following the action plan mentioned in the above blog post should fix this issue.
[All the posts are AS-IS and doesn't carry any warranty]